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Area Forecast Discussion (AFD)

Issued by Brownsville/Rio Grande Valley, TX (BRO)

FXUS64 KBRO 182140

Area Forecast Discussion
National Weather Service Brownsville TX
340 PM CST Mon Feb 18 2019

.SHORT TERM (Now through Tuesday night): West coast trough has 
settled more into the Desert SW, where it will sit through the week. 
Coastal low pressure continues to spin up today, with the frontal 
boundary stalled just south of the border and coastal waters. 
Drizzle and areas of light rain have begun to work onshore from the 
east, expected to pick up tonight into Tuesday as the low begins to 
work further north, dragging the frontal boundary back toward the 
lower Texas coast as a warm front. As the surface low works 
northeast Tuesday afternoon into Tuesday night, the boundary slides 
back southeastward as a weak cold front. Light rain and drizzle 
chances decrease Tuesday afternoon into late Tuesday night, before 
returning Wednesday morning. 

High temperatures today top off into the low 60s, with lows tonight 
ranging from near 50 across the northern ranchlands and upper 50s in 
the RGV. Highs on Tuesday become the tricky part of the forecast, 
with a weak warm front and some breaks in the cloud cover possible, 
especially across the lower RGV and coastal locations. For now, have 
settled toward the warmer GFS and leaned cooler, with near 70s south 
and east, and mid 60s north and west. 

.LONG TERM (Wednesday through Monday): A deep 530 dam 
trough/closed low at 500mb will move eastward from the Four
Corners region to the Central Plains around mid-week, with several
weak shortwaves periodically moving around the trough across 
Texas. At the surface, a coastal low will lift northward along the
coast, bringing brief southerly flow back to Deep South Texas 
early Wednesday. Models bring the front back southward as a cold 
front Wednesday afternoon, with stronger northerly winds and
little CAA. Unsettled weather will quickly return through 
Thursday as coastal troughing develops once again. Occasional
light rain and drizzle is expected, with better chances across the
RGV and coastal areas. Finally some warmer and drier conditions 
are anticipated by the end of the week Friday into Saturday with 
more persistent southerly flow returning to the CWA. The next 
storm system will track through the Plains, increasing the PGF and
allowing for breezy to windy conditions. This will also allow 
temperatures to rise well above normal with models indicating 
highs in the 80s to possibly low 90s out west. As the surface low
lifts eastward, it should bring the next cold front through late 
in the weekend, bringing much cooler temperatures during the day 
Sunday. With moisture expected to be shallow throughout the week, 
QPF is expected to be low, so there may be periods with no 
measurable drizzle/rain (0.01 or more), but still poor 
visibilities and wet roadways.


.MARINE (Now through Tuesday night): Hazardous marine conditions 
continue into Tuesday afternoon as coastal low pressure works north 
along the lower Texas coast, dragging a frontal boundary behind it. 
High pressure builds in briefly Tuesday night into Wednesday 
morning, allowing winds to decrease and seas to subside. SCAs 
persist into Tuesday afternoon, with SCEC conditions likely into 

Wednesday through Monday: Small Craft Advisory conditions are 
possible in the wake of a cold front on Wednesday, with Small 
Craft Exercise Caution conditions for the rest of the forecast 
period. Southerly flow will return towards the end of the week 
with moderate winds and seas continuing. The persistent light rain
and drizzle should also take a break as stronger low-level
returns. The next front will be possible Saturday night into
Sunday, bringing stronger north winds and building seas once


BAYVIEW/PORT ISABEL  59  68  59  63 /  50  30  30  50 
BROWNSVILLE          59  70  60  65 /  50  30  30  50 
HARLINGEN            57  69  58  65 /  50  30  30  50 
MCALLEN              56  68  57  68 /  40  30  30  40 
RIO GRANDE CITY      54  66  55  70 /  20  20  20  30 
SOUTH PADRE ISLAND   60  65  60  62 /  50  30  30  60 


GM...Small Craft Advisory until 6 AM CST Tuesday for GMZ150-155-170-



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